C79.31

HCC Category Mapping

What This Code Means

Cancer that has spread to the brain tissue itself from a primary cancer located elsewhere in the body.

Coding Tips

• •Distinguish between brain metastases (C79.31) and meningeal metastases (C79.32); brain tissue involvement versus membrane involvement requires different codes
• •Brain metastases are a serious complication requiring coordination with oncology and neurology; ensure primary cancer site is documented

Clinical Significance

Secondary malignant neoplasm of the brain is a devastating complication of advanced cancer, significantly impacting neurological function, quality of life, and survival. Brain metastases are common in lung, breast, melanoma, and renal cell cancers. Treatment requires multidisciplinary coordination involving neurosurgery, radiation oncology, and medical oncology, and these patients have high resource utilization.

Documentation Requirements

• ✓Primary cancer site documented and coded separately
• ✓Imaging confirmation — brain MRI with contrast is the gold standard
• ✓Number, size, and location of brain metastases (supratentorial vs. infratentorial)
• ✓Neurological symptoms — headache, seizures, focal deficits, cognitive changes
• ✓Treatment approach — surgical resection, stereotactic radiosurgery, whole-brain radiation, systemic therapy
• ✓Presence of cerebral edema or mass effect requiring additional coding

Commonly Confused Codes